Luminous discharge tube system



Jam 22,1935 M. PENmammal@. I. v1,988,145.9-

LUMINOUS DISHARGE TUBE SYSTEMy .Filed Feb. 15, 1952 '2 sheets-sheet 1 Jan. 22, 1935.- M. PENNYBACKER '1,983,459

` LUMINOUS ,DISCHARGE TUBE SYSTEM` v I Filed Feb. 15, 1952 v 2 sheets-sheet 2 n INVENfroR /V/ff @Myne/rm Patented Jan. 22,v 193s y i 7 v UNITED STATES PATENT OFFICE- LUMINUS DISCHARGE TUBE SYSTEM Miles Pennybacker, West Orange, N. J., assig'nor to Voltarc Tubes, Inc., Newark,` N. J., a corporation of New Jersey Application February 15, 1932, Serial No. 592.931

15 Claims. (Cl. 176-124) This invention relates to luminous discharge branch 28 of the parallel circuit. The two paraltubes utilizing an alternating voltage source of. lel branches 27 and 28 are connected across electric power. It is an object of the invention the current supply mains 14 and 15, which conto provide improved circuits for such tubes. It veniently are supplied with alternating current is a further object Vof the invention to provide of suitable voltagev by a high reactance trans- 5 an improved luminous discharge tube adapted former 16. Such high reactance transformers .for use in such circuits. Other objects and adare commonly used in this art, and, as is well vantages of the invention will appear hereinafter. known,v they serve to limit the current flowing 'Ihe nature and objects of the invention will through the load connected thereto. Connected be better understood from the description of in the branch 27 in series with the tubes 10 and 10 certain illustrative embodiments thereof, and for 11 is means indicated diagrammatically at 17 the purpose of such description reference should which offers a higher resistance to the flow of be had to the accompanying drawings forming current in one direction, for example from left a part hereof, and in which: to right, than it does to the flow of current in 16 Figs. l, 2 and 3 are circuit diagrams illustratthe opposite direction. Connected in the branch l5 ing how' a plurality of luminous discharge tubes 28 in series with the tubes 12 and 13 is similar may be supplied with power from a single source means 18. Y

of current; The means 17 and 18 are connected in re- Fig. 4 is a view of a luminous discharge tube versed direction so that one o1' the parallel 20 having substantially unidirectional vconductivity branches 27 oiers a high resistance to the flow of 20 under the circuit conditions described; and current in one direction, while the other parallel Figs. 5 and 6 are enlarged sectional views of branch 28 oiers a high resistance to the now of the electrodes of the tube shown in Fig. 4. current in the opposite direction, and the two The resistance of luminous discharge tubes branches of the parallel circuit'may be. said'to 4Si' decreases rapidly as the discharge begins. As a have substantially unidirectional conductivity in 25 result it has not heretofore been practical'to opopposite directions when connected in this man1 erate luminous discharge tubes in parallel from ner. By way of example, the means 17 and 18 a single source of current except by the use of may take the form of a suitable current rectifier, ballasting reactors or resistances in series with or ofa source of direct current.A As is ordinarily 'w each tube. `Without such reactance or resistthe case, the rectifier should not limit the cur- 30 ance one tube will discharge before the others, rent of the circuit in which it is placed, but and thereupon the resistance of the discharging should be so chosen that its maximum current is tube will decrease to such an extent that the other Well above the current required by the tubes in tubes will not discharge. Because of this fact, series therewith. luminous discharge tubes which are to be ener- It will be seen that with the arrangement 35 gized from a single source of current commonly shown in Fig. 1, as the voltage increases in one are connected in series, thereby necessitating direction during a portion of its cycle it tends to the use o i' higher voltages than would be necesdischarge through both of the parallel branches. sary if the tubes could be operated in parallel. However, one of the branches oiers a higher .lo According to this invention two luminous disresistance t0 discharge than does the other 40 charge tubes, or two branches of series-conbranch.- When the 101118.86 I'efhesA a Certain nected tubes, may be operated in parallel from value, dependent on the characteristics of 'the' a single source of alternating current without tubes and the means 17 and 18', the branch having employing separate external reactances or revlower resistancewill discharge and as that branch v4I sistances in series with each tube or parallel discharges itsA .resistance will decrease rapidly 45 branch. This is accomplished by causing one of relative to the resistance of the'other branch, the parallel branches to have a relatively high with the result that the other branch will notimpedance to current flow in one direction comdischarge. When the voltage decreases below pared to theA otheribranch, and a relatively low that necessary to sustain discharge, dischargewill 50V impedance to current ow in the opposite direccease, and as 'the-voltage passes through zero and 50 tion compared to said other branch. f increases in the opposite direction there will be Referring to Fig. 1 of the drawings, the tubes another discharge, but this time through the other 10 and 11 are connected-in series to form one of the parallel branches. It will be seen that the branch 27 of a parallel circuit and the tubes 12 tubes in the two branches discharge alternately,

and 13 are connected in series to form the other one branch discharging when the voltage is'apthe ,same direction, each in series with a suitable ballasting reactor or resistance, l)in parallel across plied in one direction, and the other branch discharging when the voltage is reversed.

The frequency most commonly used today in alternating current supply lines is 60 cycles per second, which will produce 60 discharges per second in each of the parallel branches. 'Ihis frequency issumciently high so thatthere will be no flickering apparent to the naked eye. Since each tube discharges only when the voltage is applied in one direction there will be a reduction in the brilliancy for anyone tube as compared with operation of the same tubewhen connected to discharge as the voltage is applied in each direction. For the purposes of electric sign lighting this reduction in brilliancy is .in most instances permissible, and does not appear to the naked eye to amount to or even approach the ligure of 50%. Moreover, it may be compensated for by an increase in current density, either by reducing the tubediam'eter for the same current, or by increasing the current with the same diameter. By this means an equivalent or greater apparent brilliancy may be obtained in each tube with less power consumption per unit of tube length than is obtained in the ordinary bi-directional operation, and with greater total footage of tube on the same applied voltage. Consequently, by the use of this invention the length of luminous tubes operated from a single source of current supply may be greatly increased with an apparent increase in light output for the same power input.

' 'I'he unidirectional means 1'1 and 18 shown in Fig. 1 may be dispensedwith by designing one or more of the luminous dischargetubes so that the parallel tube branches themselves have-substantially unidirectional conductivity, or offer a higher resistance to the now of current in one direction than to the flow of current inthe opposite direction. With two parallel branches of series connected tubes it may suince if a single tube has substantially unidirectional current characteristics. Referring to Fig. 2, the luminous discharge tubes 20 and 2l are connected in series, anode to cathode, to provide one branch 38 of a parallel circuit. The luminous discharge tubes 22 and 23 also are connected in series, anode to cathode,

ilow of current in one direction. while the other branch offers a relatively low resistance to the flow of ciu'rent in the opposite direction. 'It will be apparent from what has been said 'regarding Fig. 1 that normally the tubes in the branch circuit 38 will discharge only when 'thevoltage is applied in oneI direction; and the tubes in thel other branch 39 will rdischarge only when the voltage 1S reversed. 1

Applicants arrangement has distinct advantages over an arrangementin which a single unidirectional tube is connected to a source of alternating current, and also over an arrangement in which a plurality of .such tubes are connected in a source offaltemating'current. With the arrangements shown tically in Figs. l

and 2 all 'of the tubes will discharge unidirectionally, but-neither branch is required to withstand the maximum reverse voltage of the current supply mains, because the lower resistance branch will discharge before the voltage wave reaches a' maximum value.

A further advantage arising from applicant's V invention lies in the greatly increased operating life of the tubes. The life of the tube operated will be substantially doubled as compared to the `life of a similar tube with large electrodes at or more than two series of tubes in parallel across alternating current supply mains. as for example in low voltage discharge tubes, this may be donel conveniently as shown in Fig. 3. Two luminous discharge tubes 30 and 3l are connected in parallel, and the parallel circuit is connected in series with'a ballasting reactor or resistance 32 across the alternating current supply mains 33 and 34'.

v.Two othervtubes 35 and 36 are connected in par-4 allel, and this parallel circuit is connected in series with a ballasting reactor or resistance 37 across the supply mains 33 and 34. Conveniently, the tubes have substantially unidirectional conductivity, and the two ,tubes comprising each ofthe parallel circuits. are connected in reverse y direction.

With the arrangement shown in Fig. 3, the tubes 30 and 35 will discharge at substantially the same timeonly when the voltage 'is applied in one directlon,and the tubes 3l and 36 will discharge only when the voltage is reversed. The, arrangement shown in Fig. 3 contemplates the use of ballasting reactors orresistances, but since a single reactor or resistance suilices for two tubes there is a decided advantage over arrangements heretofore known in which each tube has required a separate reactor or resistance to insure satisfactory parallel operation.

, Fig. 4 shows an improved luminous dischargetube having substantially unidirectional conductivity which` when illled with neon, helium or others of the noble gases. is suitable for use in the circuits illustrated in Figs. 2 and 3. Ordinarily, such a tube will be several feet long and may be formed into suitable letters or figures. The sealed tube 40 has enlarged ends in which are a cathode 4l and an anode 42 separated by a column of rarefled atmosphere contained within l the tube. lElectrical connection may be lmade to the electrodes 4l and 42 by means of the terminals'43 and 44 passing through and sealed.

in the wall of the tube 40. -A cylindrical shield 47 of insulating material such as mica may be employed around the cathode 4l on the interior Aof the tube.

The tube illustrated in Fig. 4 has substantially unidirectional conductivity by reason of 'the fact that at the range of gas pressures normally used, 1 e. from 5 to 25 millimeters of mercury, and within thenormal-operating current range 'of from l5 to 80 milllamperes. the cathode has a relatively lowcathode drop by reason of its large area, andthe anode has a relatively high' cathode drop by reason ci `its small area. For

able at the anode, it may be said that 'in generaly the lower the drop -at the cathode during discharge and the higher the drop at thev anode during reverse voltage, the stronger the unidirectional tendency.. the more stable vthe operation of the tube, and the greater the unbalance of relative lengths of tube permitted in the two parallel branches. Applicant has found that a good working rule to follow to insure this difference in drop between the anode and the con-' 'ventional designs of cathode is to have the exposed area of the anode such' that its Vnormal current density if used as a cathode would be exceeded when current in the reverse direction is less than 2% of the normal discharge peak current.

The construction of the electrodes 41 and 42 will be better understood by reference to Figs. 5 and 6. In the illustrative embodiment the cath- 1 ode comprises a conical metal member having its open end toward the column of gas contained in the tube, and its apex connected as by welding to the terminal 43. Conveniently the conical electrode may be nickelor iron, and its inner surface may be treated to reduce the cathode fall of potential. By' using a conical electrode of narrow angle the most elcient electrode diameter is assured for all reasonable variation in gas pressure 'within the tube. 'lhe electrode 42 conveniently comprises a wire 45, which may be tungsten or nickel, connected to the terminal 44 and extending throughv the end surface of the wire 45 exposed.

, The term luminous discharge tube as\used herein is intended to vinclude tubes. bulbs and receptacles of various shapes and materials which are adapted to pass a luminous positive column electric' discharge through an vatmosphere of gases. lThe term discharge is used to describe the main body of the luminous discharge, andnot the small or transient discharge which may occur with the relatively small current which may flow in the reverse direction to the main current in each branch.

It will be apparent from the foregoing description that applicant has provided a novel circuit` for utilizing luminous discharge tubes. A plurality oftubes may be` operated from a single 'f source of alternating current with an increase in to withstand the full reverse voltage of the current supply; v p

Y The foregoing ldescription of certain specific lembodiments of the invention is illustrative merely, and is not intended cs defining the ninas of the invention.

I claim:

1. Aluminous discharge tube system comprising in vcombination a branch circuit vhaving substantially unidirectional conductivity and including at least one luminous discharge tube, a second branch circuit having substantially unidirectional conductivity and including at least one luminous discharge tube, means for.connecting said two branch circuits in parallel and in opposition to one another, a current-limiting impedance common to .said parallel branch circuits, and means for supplying alternating current to said system, whereby luminous discharge occurs alternately in the two branch circuits and neither branch io f circuit is required to withstand the full reverse' voltage of the alternating current source during 'operation of the other branch.

, brcncn circuit nai/ing nmctcnn-cuy unidirectional conductivity' and including at least one luminous discharge tube, means for connecting saidtwo branch circuits in parallel and in opposition to one another, a current-limiting' reactance common to said parallel branch circuits, and means for supplying alternating current to said system, whereby luminous discharge occurs alternately in the two branch circuits and neither branch circuit is required to withstand the full reverse voltage of the alternating current source during operation of the other branch.

3. A luminous discharge tube system comprising in combination two branch circuits each including at least one luminous discharge tube and connected in parallel, means in one of said branch circuits for permitting the flow of current substantially only in one direction and means in the other of said branch circuits for permitting the flow of current substantially only in the opposite direction, a current-limiting impedance common to said parallel branch circuits,and means for supplying alternating current to 'said system, whereby luminous discharge occurs alternately in the two branch circuits, andeach of said two unidirectional means having such characteristics that the discharge current therethrough is limited by said impedance.

l 4. A luminous discharge -tube system comprising in combination two branch circuits each including at least one luminous discharge tube and connected` in parallel, means in each of saidI branch circuits for permitting current to passin .one direction and for substantially preventing its passage in the other direction, said means in one of said branch' circuits being'connected in opposi-l tion tosaid means in the other of said branch circuits, a current-limiting reactance common to said parallel branch circuits and connected` in series therewith, and means for supplying'v alternating current to said system, whereby luminous discharge occurs alternately in the two branch circuits, and said unidirectional means oil'ering an impedance to the discharge current less than that of 4said reactance, whereby the discharge current through said branch circuits limited by said reactance.

5. A luminous discharge tube system comprisoi said branch circuits for permitting current to pass in one direction and for substantially preventing its passage in the other direction, said means in one oi said branch circuits being connected in opposition to said-means in the other of. said branch circuits, whereby luminous discharge occurs alternately in the two branch circuits, and said means oiiering an impedance to the discharge current less than that oi said transformer, whereby the current in said system is limited by said transformer.

6. A luminous discharge tube system compris- -ing in combination tw'olbranch circuits each including at least one luminous discharge tube and connected in parallel. an impedance in one oisaid branch circuits having a high impedance to'current ow in one direction and a relatively low impedance to current tlow in the opposite direction, an impedance in the other oi' said branch circuits 'having a high impedance to current ilow in the direction in which said first branch impedance has its low impedance and having a relatively low impedance to current ilow in the opposite direction, a current-limiting reactance `common t'o said parallel branch. circuits and connected in series therewith, and means -for supplying alternating current to said system, whereby luminous discharge. occurs alternately in the two branch circuits, and said two branch circuit impedances having such characteristics with respect to the characteristics of saidlluminous tubes and said reactance that the current ilow in said system is limited by said reactance.

7. A luminous discharge tube system compris'- ing in' combination twobranch circuits each' including at least one luminous discharge tube and connected in parallel, a. gaseous conduction' rectifier in one of said branch circuits permitting the flow of current substantially'only in one direction. and a gaseous conduction rectier in the other of said branch circuits permitting the flow oi current substantially only inlthe opposite direction, a current-limiting reactance com position to one another, a current-limiting impedance common to said parallel branch cir.

;cuits and connected in; series therewith,and means tor supplying alternating current to said system, whereby' luminous discharge all ternately inthe twobranch circuits and the disvcharge current therethrough is limited by said 9. A luminous discharge.v tube system comprising in combination two branch circuits each including a 'plurality of substantially unidirectional luminous discharge tubes connected in series with the anode ci one tube connected to 4the cathodeoi the next. means' for connecting said two branch circuits in parallel andin epposition to one another.) current-limiting reactance common to said parallel branch circuits, and means for supplying alternating current `to' said system, whereby luminous dischargeoccursslternatelyin the two branch circuits and the discharge current therethrough is limited by said reactance.

10. A luminous discharge tube system compris- '.ing in combination a step-up high reactance transformer having a primary and a. secondary, a

`source oi alternating current connected to said primary, two branchv circuits each including a. plurality of substaantially unidirectional luminous discharge-tubes connected in series 'with the anode of one tube connected tothe cathode of the next, and means for connecting said two branch' circuits in parallel and in opposition to one an 11. A luminous discharge tube system 'compris- I ing in combination two vbranch circuits each includingat least one substantially unidirectional luminous discharge tubefhavingv a cold cathode and an anode, the exposed areav oi said cathode being at least thirty times greater than the exposed area of said anode, means for connecting said two branch' circuits in parallel and in opposition to one another, a current-limiting impedance common to said parallel branch circuits and connected in series therewith, and means for supplying alternating current to said system, whereby luminous discharge occurs alternately 4in the twobranch circuits and the dischargecurrent therethrough is limitedby ysaid impedance. l

12. A luminous discharge tube system comprising `in 'combination 'a step-up high'reactancel transformer having a primary and a secondary, a source of alternating current connected to 'said primary, two branch circuits eachincluding a plurality .of substantially unidirectional luminous discharge tubes having a cold cathode' and an anode connected in series with the anode oi one tube connected to the cathode of the next, the exposed'area of said cathode being at least thirty times greater than the exposed area of said anode, and means for connecting said two branch circuits in parallel and in opposition to one another. across said secondary, whereby4 luminous discharge occurs alternately in the two branch circuits and the discharge current therethrough 4is limited by said transformer.

13. A luminous discharge tube system comprising in combination two'l branch circuits .each including atleast o ne substantially unidirectional luminous discharge tube, means for connecting said two lranch circuits in parallel and in opposition to one another, a current-limiting resistance common to said parallel branch circuits 4and connected in series therewith, and means for supplying alternating current to said system,

whereby luminous discharge alternately in thek two branch circuits and the discharge current therethrough is limited by said resistance.

14. A luminous discharge tube system comprising in combination a source of alternating 'curren and a plurality oi luminous discharge tube 'circuits connected in parallel across said source, 'Y each yoi said circuits consisting of two .branch circuits each including at least one substantially unidirectional luminous'discharge tube, means -for connecting said two branch circuits in paraliel andin opposition to one another, anda current-.limiting impedance common to said parallel branch circuits' and connected in series therewith, whereby'luminous discharge occurs alternstely in tbetwo branchcircuits and charge current therethrough is limited by said impedance.

f 15.- A luminous discharge tube system comprising in combination two branch circuits each including at` least one luminous discharge ',tube, a discharge tube in at least one of said branch circuits having substantially unidirectional conductivity, means for connecting said'two branch circuits in parallel, an impedance common to s'aid parallel branch circuits and connected in series therewith, and meansior supplying alternating curr v to said system, the electrical characteristics o said system being such that luminous discharge occurs aitemately in the two branchv mms PENNYBACKER. 'l 

